1. Field of the Invention
The present invention relates to a hybridoma cell line producing a monoclonal antibody against foot-and-mouth disease virus (FMDV), the monoclonal antibody therefrom, a reagent and kit for enzyme-linked immunosorbent assay (ELISA), and an immunoassay method. More particularly, the present invention relates to a hybridoma cell line applicable to sandwich ELISA and capable of producing an anti-FMDV NSP (Non-structural protein) monoclonal antibody, the monoclonal antibody therefrom, and an immunoassay reagent and kit including the monoclonal antibody.
2. Description of the Prior Art
Foot-and-mouth disease (FMD) is one of the most contagious diseases among artiodactyla, primarily infecting farm animals such as cows, pigs, and sheep. Typical symptoms of FMD are fever, and formation of epithelial blisters and subsequent necrosis thereof affecting the mouth, tongue, nostrils, legs, and nipples. The foot-and-mouth disease virus, a positive strand RNA virus known as Aphthovirus, Picornaviridae in taxonomy, is a tiny non-enveloped virus that has 8.5 kbp of genome translatable into structural proteins (SPs) and non-structural proteins (NSPs). There are seven FMDV serotypes, known as serotypes O, A, C, Asia 1, SAT 1, SAT 2, and SAT 3 (SAT=Southern African Territories), recognized worldwide. The serotypes do not provide cross protection for each other. FMDV mutates quickly and hence presents genetic and antigenic variation between strains. VP1 structural protein on the surface of FMDV shows major neutralization activity with high plasticity and marked antigenic variation. In 1997, heath crisis of Taiwan's animal populations triggered by an outbreak of serotype O FMD epidemic; and the serotype O FMDV was named O/TAW/97. This strain is a prototype of atypical porcinophilic infection in swine. According to experiment results, the codon of a segment (93-102) within the non-structural protein region 3A of the strain is deleted and the segment is a major factor in restricting the growth and replication of the virus in bovine epithelial cells in vitro. Hence, the deletion of the virus strain is proved to be the cause of a lack in bovine susceptibility to the O/TAW/97 strain. The 1997's FMD epidemic in Taiwan caused a great economic loss (estimated at more than US$ 6 billions) because of control measures and trade restrictions. Another virus strain, which was discovered in subclinically infected cattle in Kinmen, has a gene structure with a full-length 3A non-structural protein translation region, and thus is proved to be a pernicious bovine virus strain (O/TAW/2/99). The O/TAW/2/99 strain, which is a topotype of the serotype O FMDV prevalent in southern Asia, launched its first invasion into Taiwan in 1999. Upon the FMD outbreak, the Taiwanese government took quarantine measures immediately, screened animals in the affected farms for FMDV, humanely killed any infected animals promptly, and disposed of the carcasses without delay. In addition, the Taiwanese government carried out precautionary screening of farms suspected of FMDV infection, as an action taken to confine the spread of FMDV.
The conventional ways of producing inactivated viruses have the following drawbacks: (1) With FMD being a highly contagious airborne disease, and the production of inactivated FMDV entailing the use of viruses, the laboratories where inactivated FMDV is to be produced must be Class III negative pressure laboratories conforming to corresponding bio-safety specifications, and nevertheless there is a risk that FMDV may be released in the course of production; (2) An inactivated virus cannot produce the non-structural protein which would otherwise be produced naturally by an infected living host, and in consequence a diagnostic immunoassay using the inactivated virus as antigen is unable to distinguish infected living host from vaccinated ones.